For many years, perishable goods such as foodstuffs have been stored in sealed trays or containers. Press-formed paperboard trays are typically formed by pressure forming a single sheet or blank of material, which may comprise multiple layers that have been laminated together, into a predetermined shape, or by folding and adhering the sheet or blank into the desired tray shape. Once assembled, the tray may be filled and closed.
Typically, gaps in the tray surface created during the pressure forming or folding of the tray present avenues for gas and moisture to enter the tray that has been sealed by known means (for example, a lid film). For example, many modern trays are pressure formed in a mold that creates pleated or crimped corners, walls, rims, or flange areas as a byproduct of forcing the tray into a desired shape. As a further example, trays formed by folding a blank generally have overlapping partial walls that are imperfectly adhered to one another, leaving irregularities between the walls where no adhesive is present.
Many times, trays are sealed with a separate lid, plastic film, or other top designed to minimize airflow or vapor flow into the tray interior. Few such barriers, however, form a perfectly hermetic seal. The aforementioned gaps and irregularities prevent the tray and top from uniformly mating, because the top is insufficiently flexible to fill in such minute spaces in the rim or flange areas of the tray. Thus, even though a partially effective seal may be created, the tray contents are nonetheless exposed to some amount of external air and moisture seeping through these gaps. This in turn accelerates the spoiling of the tray's contents.
Further, many trays or containers are relatively flimsy. Oftentimes a tray may buckle under a comparatively light weight due to inherent weaknesses in the paperboard material and processes used to form the tray. That is, the tray sidewalls do not provide sufficient support to prevent the tray from bending, folding, or torquing when a load is placed on the tray. Such trays may also become substantially weaker if they are exposed to high moisture environments, such as those present in a refrigerator, microwave over, or freezer.
A tray may also be difficult to carry, due to its size and awkwardness. Especially large trays, whether circular or rectangular, easily shift masses placed thereon when the tray is carried from beneath. This in turn changes the balance of the tray and may cause the tray to be dropped. Similarly, many large trays are too flimsy to be carried by the edges, or lack a good gripping area along the edges.
Many cooking trays may be loaded with different types of food and heated in an oven, microwave, or other suitable appliance. As these foods heat, they may run together, creating an unappetizing appearance and taste. Further, a cooking tray may unevenly distribute heat across its interior surface, causing food in different portions of the tray to heat unevenly. Finally, many cooking trays are not reusable or washable, because the tray material cannot withstand immersion in water or detergent.
Accordingly, there is a need in the art for an improved tray.